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机械毕业设计全套

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JX01-032@4T焊接滚轮架机械设计,机械毕业设计全套

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Removing and Replacing Welded-On Covers Technical Data 1LUS070005-LFE Rev 5 October 15, 2003 Instruction Leaflet Scope This leaflet contains general procedures to be followed from the time the transformer and its accessories are received, until it is put into operation. These instructions do not purport to cover all possible contingencies that may arise during installation, operation, maintenance, and all details and variations of this equipment. If you require additional information, contact ABB Small Power Transformers in South Boston, Virginia. The welded-on cover of a small power transformer may be removed by chipping out the joining weld or by cutting out the weld with an arc-air torch or grinder. The following procedures also include recommended equipment. Chipping Out a Weld Recommended Equipment 1. Pneumatic chipping hammer. 2. Diamond-pointed chisels, 3/8 and 1/8-inch. The chisels should be forged tools, hardened and tempered so that the edges will not turn or spall. The cutting edges of the diamond-pointed chisels should be ground straight with no chamfer. 3. Flat chisels. The flat chisel should have the flat side relieved 1/64-inch, approximately 1/8-inch back from the cutting edge. This prevents the chisel from “digging in” and allows the operator better control of its cutting. 4. Gloves and safety glasses. Procedure It is important to cover any openings in the tank to avoid entry of chips. To remove a weld by chipping, apply machine oil or grease to the surface of the weld to lubricate the cutting. A 3/8-inch diamond-point chisel is used in pneumatic hammer and the chisel is held so that the diamond is pointed to the root of the joint. The chisel should cut 1/8-inch back of the vertical edge of the weld and along the face of the horizontal flange to remove as much of the weld as possible. Should the weld not be completely removed in one pass with the 3/8-inch diamond-point chisel, more oil or grease should be spread over the remaining weld and the flat chisel used to cut the weld flush with the horizontal and vertical surfaces of the joint. Use the small diamond-point chisel to remove any remaining weld metal from the root of the joint. Drive the flat chisel into the root of the joint to crack the seal. Move it slowly to prevent the chisel driving into the joint and deforming the plates. A lifting force on the cover will help break the seal. ntsArc Air Cutting Recommended Equipment 1. An AC or DC welding machine. 2. A manual “Arc Air” torch. 3. Copper-clad AC or DC carbon electrodes. 4. An air supply-80lb. gauge. 5. Flat chisel and hammer. 6. CO2 fire extinguisher, welding helmet, safety goggles, gloves. Procedure Raise the liquid level up to the highest possible point. Cover external bushings, gauges and lighting arrestors. Connect the supply of dry nitrogen to the filling plug and flush the gas space with nitrogen. Loosen hand hole cover for nitrogen to escape. Keep the nitrogen flowing while the weld is being removed to blanket the core and coils and to prevent combustible gases from collecting. Strike an arc at one corner of the tank forming a molten pool of metal. Introduce the air and start moving the torch. Keep the driving force of the arc parallel to the weld path. Remove the complete weld in one pass. If the weld is too large to remove in one pass, reduce the size of the electrode and repeat. Clamp the side or sides to prevent the joint opening before all the weld is removed. Remove C-clamps and break the seal with flat chisel. Dont damage the tank flange or cover. Replacing a Welded-On Cover Preparing the Cover 1. Chip or grind any irregularities around the cover edge left during the weld removal operation when the cover was removed from the tank. The cover edge should be square and expose clean metal. 2. Clean the underside of the cover three inches back from the cover edge to a smooth surface. A disc grinder is recommended. 3. Remove and wipe all foreign material from the cover, especially from the underside to prevent dirt falling into the transformer when the cover is placed in position on the transformer tank. Preparing the Tank Flange 1. Place a blanket of clean paper or cloth over the entire transformer a few inches below the tank flange. This blanket should be attached and sealed with wide masking tape. This is necessary to prevent any foreign material falling into the transformer. 2. Remove any raised irregularities from the top surface of the flange by chipping or grinding. A sanding disc will do the job very effectively, or a grinder may be used. In either case, it should be used so that the material removed from the flange will be thrown away from the transformer tank rather than into it. This surface must be smooth to permit the cover to fit tightly and uniformly around the tank. nts3. Gently brush cuttings and debris collected on the blanket over the transformer to the center of the blanket. Remove this debris, then carefully pull the sealing tape from the tank walls to free the blanket. Make certain that the edges of the blanket are kept above the center of the blanket at all times so that any debris will not roll into the transformer. Applying the Braided Glass Sleeve Sealing Gasket to the Tank Flange 1. Brush on a -inch wide coating of gasket cement 1-1/2 to 2-inches back from the edge of the flange completely around the tank. Care must be observed to prevent any cement extended onto the weld area as it will cause weld porosity. 2. Place 1/8-inch dia. Braided glass sleeve completely around the tank flange in the center of the freshly-applied cement. There must not be any openings in the gaskets. Use a butt joint, or allow one end to extend a little in the back of the other. Positioning the Cover and Preparing for Welding 1. Lower the cover onto the tank flange so that it is in its approximate final position without sliding across the braided glass sleeve gasket. Normally the flange will extend approximately -inch beyond the cover edge. 2. Clamp the cover and flange tightly together around its entire periphery with C-clamps. Place the C-clamps near the edge of the cover so that the operator can weld under the clamps. The cover edge should be tight against the flange before any welding is done. Welding the Cover to the Flange 1. Cover all openings in the cover. 2. Apply a 1/8-inch fillet sealing weld around the cover starting at one corner of the tank and welding around it. Use ZIP 14 (AWS 7040) AWS 6013 welding electrode. Either AC or DC current may be used. Use the current setting recommended for the electrode. 3. Remove the C-clamps from the cover and flange. 4. Remove the slag from the weld bead and wire brush. 5. Weave a -inch fillet weld over the 1/8-inch fillet weld using 5/32-inch diameter FP electrodes and a welding current of 150 to 160 amperes. This is also a coated electrode, an American Welding Society Type E-6012, and may be used with AC or DC (straight polarity preferred) current. 6. Clean the slag from the weld. Paint the weld, flange and the covers edge with primer and touch-up paint. Renewal Parts Contact ABB Small Power Transformers in South Boston, Virginia, for repair and replacement information at (434) 572 5695. nts Disclaimer of Warranties and Limitation of Liability THERE ARE NO UNDERSTANDINGS, AGREEMENTS, REPRESENTATIONS, OR WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OTHER THAN THOSE SPECIFICALLY SET OUT BY AN EXISTING CONTRACT BETWEEN THE PARTIES. ANY SUCH CONTRACT STATES THE ENTIRE OBLIGATION OF THE SELLER. THE CONTENTS OF THIS DOCUMENT SHALL NOT BECOME PART OF OR MODIFY ANY PRIOR OR EXISTING AGREEMENT, COMMITMENT OR RELATIONSHIP. The information, recommendations, description and safety notations in this document are based on our experience and judgment with respect to Transformers. THIS INFORMATION SHOULD NOT BE CONSIDERED TO BE ALL INCLUSIVE OR COVERING ALL CONTINGENCIES. If further information is required, ABB Inc. should b